1. Field of the Invention
The present invention relates to food products and to their methods of preparation. More particularly, the present invention relates to beverages comprising both juice and dairy products.
2. The Prior Art
Numerous efforts have been made in the past to provide beverages which combine dairy ingredients and juice ingredients, particularly fruit juices. Relatively large amounts of juice are required to give a characteristic juice flavor to the milk, particularly with relatively mild flavored juices such as orange juice. However, when the acidic juice fraction is added to milk in sufficient amounts so as to lower the milk pH from the natural pH of 6.4-6.7 to below the isoelectric point of the milk's casein protein, then the protein precipitates and/or curdles. Additionally, over time various precipitates can form. Collectively, these problems are referred to herein as "instability." Most previous art efforts have attempted to prepare juice-milk drinks using acidified or soured milk and especially acidified skim milk rather than sweet milk (i.e., milk at its natural pH).
Typically, such past efforts to prepare a sour beverage have employed an added stabilizer (see, for example, U.S. Pat. No. 4,212,893 issued July 15, 1980 to J. Takahata wherein locust bean gum is used as a stabilizer) or uses the pectin associated with the fruit or added pectin (see, U.S. Pat. No. 4,031,264 issued June 21, 1977 to Arolski et al.; U.S. Pat. No. 3,764,710 issued Oct. 2, 1973 to Inagami et al.; U.S. Pat. No. 3,625,702 issued Dec. 7, 1971 to H. Exler; U.S. Pat. No. 2,818,342 issued Dec. 31, 1957 to E. Ransom; and U.S. Pat. No. 3,174,864 issued Mar. 23, 1965 to Johnston et al.).
Still another approach has been to prepare drinks using only milk derived materials or milk fractions, i.e., materials not containing the proteins which would precipitate at lower pH values.
U.S. Pat. No. 4,061,792 (issued Dec. 6, 1977 to K. Inagami et al.) disclosed still another approach. There, fruit juices are first contacted with acidified solutions of proteins to react with juice tannins to form coagulums. The coagulums are then removed from the juice to yield tannin-free juice which it is taught can be added to acidified milk to provide sour juice-milk beverages with reduced curdling tendencies.
It has been surprisingly discovered that the stability problems are due in part to the various cations and also to the anions supplied from the several beverage constituents, i.e., from the various minerals. The present invention provides a demineralized, (i.e., decationized and deanionized and thus improved stability, juice-milk beverage compared to the prior art products, further provides both juice and milk components useful in the preparation of such beverages, and provides new methods of preparing both these components and the finished beverages. In one aspect, the improvement resides in the provision of a relatively high pH or "low-acid" beverage product compared to prior art products which nonetheless exhibits minimal undesirable curdling and/or precipitation even at high juice solids levels. The present invention also provides such relatively high pH beverages with high juice solids even with high protein levels. This is surprising since the curdling problems generally increase as either the protein level or juice solids level increases.
Even more importantly from a commercial standpoint, in one embodiment of the present invention, the improved stability juice-milk beverages contain no added ingredients, i.e., are free of added stabilizers, emulsifiers, acidulants or the like. Such beverages are perceived by the consumer as being "all-natural," thus more healthy, and are therefore more desirable than the products of the prior art.
In its method aspect, the present invention provides a surprising combination of ion exchange processing for the separate provision of a juice component and of a milk component. Although milk has been treated using a similar cation exchange (see, U.S. Pat. No. 4,352,828 issued Oct. 5, 1982 to Rialand et al.), the present invention employs both a cationic as well as a novel, subsequent anionic exchange treatment of the milk to prepare the present novel milk components with subsequent blending and treatment to provide the beverage products of the present inventions. With regard to the juice component, the present invention provides a novel cation/anion/cation exchange process to prepare the present juice component. Additionally, the present invention provides a method for preparing a juice-milk beverage.